PEB2041

The PEB2041 is a memory time switch device. It can connect any of 512 PCM input channels to any of 25 output channels. The input information of a complete frame is stored in the on - chip 4 kbit speech memory SM. (See Figure 2.1 The incoming 512 channels of 8 bits each are written in sequence into fixed positions in the SM. This controlled by the input counter in the timing control block with a 8 kHz repetition rate. For outputting, the connection memory (GM) is read in sequence. Each location in CM points to a location in the speech memory. The byte in this speech memory location is read into the current output time slot. The read access of the CM is controlled by the output counter PEB2041 also resides in the timing control block. Hence the GM needs to be programmed beforehand for the desired connection. The CM address corresponds one particular output time slot and line number. The contents of this CM address points to a particular input time slot and line number (now resident in the SM). In the following chapters the functions of the PEB2041 will be covered in more detail.

Digital exchanges put calls of PEB2041 through by newly arranging the speech signals coded with 8-bit words (PCM time slots). The code words are transmitted serially on PCM lines. The sampling frequency of 8 kHz produces PCM frames with a duration of 125 us. The transmission rate on the line determines how many code words (speech channels)PEB2041 can be accommodated within a sampling period. With a data rate of 2048 kbps for example, there are 32 time slots of 6 bits each. 4 lines with a data rate of 8192 kbps have a transmission capacity of 512 channels. ln a digital switching matrix one distinguishes between two basic switching principles: time - division multiplex and space - division multiplex. A method that is frequently used involves a combination of the two principles, this being called spaceltime division multiplex. Figure G.1 illustrates the different principles.

The features of PEB2041 are timelspace switch for 2048, 4096 or 8192 kbps PCM systems, switching ot up to 512 incoming PCM channels to up to 256 outgoing PCM channels, tristate function for further expansion and tandem operation, non blacking switch 512`512 can built with two devices, 16 input and 8 output PCM lines, different kinds of modes (2048, 4096, 8192 kbit/sec or mixed mode), space, time, spaceffime switch mode, 8 bit P interface, single + 5 power supply, advanced low power CMOS technology, pin and soltware compatible to the FEB 2040.